Partially passivated quantum dots, process for making, and sensors therefrom

Abstract

A partially passivating core shell particle includes a luminescent nanocrystal core, and a partially passivating semiconducting core shell on a surface of the nanocrystal. The shell allows selected analytes to alter a luminescent response of the core shell particle. A quantum dot-based sensing system includes at least one partially passivating core shell particle, a light source for irradiating the partially passivating core shell particle, and a light detector for receiving emissions from the particle, wherein emissions from the core shell particle change in response to the presence of at least one analyte.

1. A core shell particle, comprising:
 a luminescent nanocrystal core, and 
 a partially passivating semiconducting shell on a surface said nanocrystal, and 
 an analyte selective shell covalently attached to said semiconductor shell. 
 
     
     
       2. The core shell particle of  claim 1 , wherein said nanocrystal comprises a metal chalcogenide and said semiconductor shell comprises a compositionally different metal chalcogenide. 
     
     
       3. The core shell particle of  claim 2 , wherein said nanocrystal comprises CdS and said semiconductor shell comprises ZnS or ZnSe. 
     
     
       4. The core shell particle of  claim 1 , wherein said nanocrystal includes a transition or lanthanide metal dopant. 
     
     
       5. The core shell particle of  claim 1 , wherein said semiconductor shell provides a band gap of at least 4 eV at 25° C. 
     
     
       6. The core shell particle of  claim 1 , wherein said analyte selective shell comprises a Macro-Cyclic Crown Ligand (MCCL). 
     
     
       7. A quantum dot-based sensing system, comprising:
 at least one core shell particle including a luminescent nanocrystal core, and 
 a partially passivating semiconducting shell on a surface said nanocrystal, 
 an analyte selective shell covalently attached to said semiconductor shell; 
 a light source for irradiating said core shell particle, and a 
 light detector for receiving emissions from said core shell particle, wherein said emissions change in response to the presence of at least one analyte. 
 
     
     
       8. The system of  claim 7 , further comprising at least one optical fiber including a transmitting leg and a receiving leg, and a core portion located between said transmitting leg and said receiving leg covered with at least one of said core shell particles. 
     
     
       9. The system of  claim 7 , wherein said analyte selective shell comprises a Macro-Cyclic Crown Ligand (MCCL). 
     
     
       10. The system of  claim 7 , wherein said nanocrystal comprises a metal chalcogenide and said semiconducting shell comprises a compositionally different metal chalcogenide. 
     
     
       11. The system of  claim 10 , wherein said nanocrystal comprises CdS and said semiconducting shell comprises ZnS or ZnSe. 
     
     
       12. A method of sensing analytes, comprising the steps of:
 providing at least one core shell particle comprising a luminescent nanocrystal core and a partially passivating semiconducting shell on a surface said nanocrystal, and an analyte selective shell covalently attached to said semiconductor shell; 
 exposing a fluid suspected of including at least one analyte to said core shell particle, and 
 determining whether said analyte is present in said fluid based on a change in luminescent response of said core shell particle following exposure to said fluid. 
 
     
     
       13. The method of  claim 12 , wherein said fluid comprises water. 
     
     
       14. The method of  claim 12 , wherein said analyte is selected from the group of heavy metal cations. 
     
     
       15. The method of  claim 14 , wherein said heavy metal cation comprises Hg, Cd or Pb. 
     
     
       16. The method of  claim 12 , wherein when said analyte is present in said fluid said change in luminescent response of said core shell particle following exposure to said fluid comprises an enhanced luminescent response. 
     
     
       17. The method of  claim 12 , wherein said analyte selective shell comprises a Macro-Cyclic Crown Ligand (MCCL).